1. Field of the Invention
This invention relates to a method and apparatus for processing photosensitive material. More specifically, this invention provides a method and apparatus for processing photosensitive material which utilizes pulsed infrared sensing replenishment system which senses photosensitive materials without producing undesirable photo exposure effects and an improved transport system having successive pairs of novel, driven roller. Photo exposure is avoided by utilization of very brief pulses of infrared energy.
2. Description of the Prior Art
Conventional photographic film/print processors include among various other systems replenishment and transport systems. Replenishment systems currently have metering devices which automatically replenish a pre-selected quantity of chemical replenisher to the chemical tanks when paper is fed into the processor. The most popular metering devices employed today are micro sensing switches which are located on the feed table; the number of switches needed vary in accordance with the width of the processor. As paper is fed over the feed table and into the feed slot, it depresses at least one of the sensing switches in order for its width to be determined. At least one of the sensing switches has to be depressed for ensuring proper replenishing of chemicals by a replenishment timer printed circuit board which regulates the replenishment action through a replenishment cabinet by the relayed impulses transmitted from the micro sensing switches and a revolution counter switch. The revolution counter switch detects the running length of paper as it passes through the processor, and the replenishment cabinet includes flowmeters and solenoids which allow the passage of replenishment chemicals upon reception of relayed impulses from the replenishment timer printed circuit board. This replenishment system is plagued with the fact that quite sensitive photographic materials can not be passed over the micro sensing switches because of the abrasive damage caused by the depressing. Also, this prior art replenishing system is inaccurate and demands a lot of the operator's time in operation.
Conventional transport systems have a complex problem in transporting a length of film, having a delicate emulsion layer, through the various stages of a developing process. One of the primary problems experienced in continuous movement processors is bromide drag. Most of the prior art today transport the film by driven rollers held against each other by spring action. As the film passes through the rollers, a squeegee action takes place causing the bromide salts to build up behind the rollers, creating what is known in the trade as "bromide drag". Another serious problem with solid rollers is the build up of silver and other deposits on the rollers which must be removed and cleaned periodically. Solid rollers require a complex spring tensioning arrangement holding one roller against the other to maintain the close tolerances that are necessary.
Another prior art method utilizes solid rollers in combination with woven plastic belts. This system has a streaking problem on the film, due to the belt pressure, and includes a complex apparatus to handle the distortion and stretch of the belts.
Therefore, what is needed and what has been invented is an improved process and photographic film processor for developing photographic material; the processor includes an improved replenishing system and an improved transport system which do not have the foregoing major deficiencies.